In the manufacture of heat exchangers or other devices filled with
compressed gases or liquids, efficient detection of leaks is a critical process.
Photoacoustics has been used to quickly detect these leaks in an industrial
environment. Although this technology can detect leaks as small as 10[sup -6]
standard cc/s, it has not been extended to localization or quantification of
these leaks. This work aims to resolve these issues. An acoustic source strength
based on the Beer-Lambert law and gas diffusion from a point source is developed
and used to predict photoacoustic signals. The relationship between
photoacoustic signals and leak test parameters, specifically leak rate,
modulation frequency, and laser power, are presented. An effective strategy for
illuminating the suspected leak area is shown, and leak detection using multiple
microphones is discussed. A carbon dioxide laser tuned to 10.6 microns is used
as the radiation source with sulfur hexaflouride as the tracer gas. Comparisons
are made between theoretical predictions and experimental results. [Work
sponsored by Ford Motor Company.]